Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 050929
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
329 AM MDT THU MAY 5 2016

.SYNOPSIS...MILD SOUTHERLY FLOW WILL PREVAIL ACROSS THE REGION
THROUGH TODAY. A SLOW MOVING PACIFIC STORM SYSTEM WILL CROSS THE
REGION FRIDAY THROUGH THE UPCOMING WEEKEND.

&&

.SHORT TERM (THROUGH 18Z SUNDAY)...
WATER VAPOR LOOP SHOWS THE RIDGE SHIFTING INTO THE ROCKIES WITH A
SPLIT TROUGH NEARING THE WEST COAST. AMDAR 400-250MB WIND
OBSERVATIONS PLACE A CYCLONIC 100-120KT JET OVER THE EASTERN
PACIFIC AND INTO CENTRAL CALIFORNIA. GOES/HRRR/00Z KSLC RAOB
INDICATE THE PRECIPITABLE WATER VALUE RANGES FROM 0.15"-0.25"
MOUNTAINS TO 0.40"-0.55" MOST VALLEYS.

WITH THE THERMAL RIDGE OVERHEAD...AND GUSTY SOUTH WINDS...EXPECTING
A VERY WARM DAY TODAY. GUSTS MAY NEAR ADVISORY LEVELS ACROSS A FEW
WESTERN VALLEYS THIS AFTERNOON AS 700MB WINDS INCREASE TO 30-35KTS
WITH 8-10MB/6HR PRESSURE FALLS THOUGH GRADIENT DOESNT LOOK TOO
STRONG.

EXPECT ISOLATED CONVECTION TO DEVELOP ON THE HIGHER TERRAIN THIS
AFTERNOON. SHORT RANGE ENSEMBLES SUGGEST INCREASING INSTABILITY
PERSISTING THROUGH TONIGHT AND FRIDAY MORNING PARTICULARLY ACROSS
EASTERN AND NORTHERN ZONES. SNOW LEVELS LOOK TO BE 8-10KFT IN THE
WARM SECTOR.

CONVECTION FRIDAY INTO SATURDAY WILL BE DRIVEN BY ARRIVAL OF COLD
POOL ALOFT ACROSS THE SOUTHERN ZONES THOUGH SREF INDICATES RIBBON ON
BEST INSTABILITY TO REMAIN NORTH AND EAST OF THE CLOSED LOW. THUS
HAVE PRETTY BROAD BRUSH OF SCATTERED CONVECTION IN THE FORECAST AT
THIS TIME WITH CLOUDS BEGINNING TO FILL IN.

SHORT RANGE ENSEMBLES INDICATE AT LEAST 30 KNOTS OF EFFECTIVE SHEAR
ACROSS THE NORTH IN THE DEEPER INSTABILITY ESPECIALLY FRIDAY. THIS
COULD HELP TO SUSTAIN ORGANIZED CONVECTION. THOUGH FORECAST
SOUNDINGS SHOW INVERTED-V DEEP MIXING UP TO 500MB SO LOCALLY STRONG
WIND GUSTS ARE THE PRIMARY THREAT FROM THIS CONVECTION.

MAIN PORTION OF THE CLOSED LOW EVOLVES INTO SOUTHERN WYOMING
SATURDAY NIGHT...WITH WRAP AROUND MOISTURE POTENTIALLY MOVING IN
FROM WYOMING BY SUNDAY MORNING.

.LONG TERM (AFTER 18Z SUNDAY)...
GFS AND EC SHOW THE CENTER OF THE CLOSED LOW OFF IN EASTERN
WYOMING BY MID DAY SUNDAY. THEY BOTH SHOW WEAK WARM ADVECTION
WRAPPING AROUND THE BACKSIDE OF THE LOW ACROSS NORTHERN PORTIONS
OF THE CWA SUNDAY AFTERNOON/EVENING. THIS LOOKS LIKE THE BEST
POTENTIAL FOR WIDESPREAD PRECIPITATION ASSOCIATED WITH THIS
WEEKEND STORM SYSTEM. HAVE ADJUSTED POPS UP TO LIKELY ACROSS THE
CENTRAL AND NORTHERN WASATCH FRONT. FARTHER SOUTH ALONG THE NATURE
OF THE PRECIPITATION APPEARS TO BE MORE SCATTERED.

A SECONDARY WAVE AND ASSOCIATED COLD FRONT WILL INCREASE THE
NORTHWEST 700MB FLOW MONDAY AFTERNOON WHICH SHOULD LOWER THE PCPN
THREAT OVER THE NORTHWEST GSL DESERT WHILE INCREASING THE THREAT OF
ALONG THE WASATCH FRONT A LITTLE. FARTHER SOUTH THIS NORTHWEST FLOW
WILL HAVE A DRYING EFFECT ON THE AREAS ALONG THE ARIZONA BORDER.
REMOVED POPS THERE MONDAY.

AS THE COLDER AIR ALOFT MOVES IN OVER NORTHERN PORTIONS OF THE CWA
TUESDAY THE THREAT OF SHOWERS WILL INCREASE. HAVE INTRODUCE LOW POPS
AND SLIGHTLY LOWER TEMPS FOR MUCH OF THE NORTHERN PORTION OF THE CWA
FOR TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING. AFTER THIS THE
TEMPS ALOFT WILL WARM FASTER THAN THE 700MB TEMPS RESULTING IN A
MORE STABLE AIR MASS. HAVE REMOVED ALL POPS FOR THE CWA FROM
WEDNESDAY AFTERNOON FORWARD. TEMPERATURE WILL WARM TO ABOVE NORMAL
ONCE AGAIN BY THURSDAY.

&&

.AVIATION...SOUTHERLY WINDS WILL PREVAIL AT THE SLC TERMINAL
THROUGH THE TAF PERIOD. WINDS ARE EXPECTED INCREASE BETWEEN 16 AND
18Z WITH GUSTS POTENTIALLY EXCEEDING 25 KTS. THERE IS A 15% CHANCE
OF HIGH BASED THUNDERSTORMS BETWEEN 00 AND 06Z THIS EVENING WHICH
COULD PRODUCE STRONG ERRATIC WINDS.

&&

.FIRE WEATHER...QUITE WARM AND DRY TODAY WITH WITH GUSTY SOUTHERLY
WINDS SETTING UP A GUSTY WIND/LOW RH EVENT THIS AFTERNOON. FRIDAY
THROUGH THE WEEKEND APPEAR TO BE COOLER AND MORE MOIST WITH
SCATTERED SHOWERS AND THUNDERSTORMS.

ANOTHER COLD FRONT MONDAY INTO TUESDAY KEEPS A MOIST AND COOLER
REGIME IN PLACE.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

$$

SHORT TERM/FIRE WEATHER...ROGOWSKI
LONG TERM/AVIATION...STRUTHWOLF

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)


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